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Hematology and Clinical Microscopy Glossary - College of American ...

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Cerebrospinal Fluid (CSF) <strong>and</strong> Body Fluid Cell Identification<br />

abundant, basophilic <strong>and</strong> agranular. Often it shows an<br />

uneven or grainy texture. Degenerative changes may<br />

occur including multiple small vacuoles or cytoplasmic<br />

blebs. Overall, the appearance <strong>of</strong> synovial lining cells<br />

is similar to that <strong>of</strong> mesothelial cells in serous fluids. Their<br />

presence in synovial fluid is expected <strong>and</strong> has no<br />

diagnostic significance.<br />

Ventricular Lining Cell (Ependymal or<br />

Choroid Cell)<br />

Cells lining the ventricles (ependymal cells) or choroid<br />

plexus (choroidal cells or choroid plexus cells) may be<br />

shed into the CSF, particularly in neonates or in the<br />

presence <strong>of</strong> a ventricular shunt or reservoir. Choroidal<br />

<strong>and</strong> ependymal cells are not diagnostically significant<br />

but must be distinguished from malignant cells.<br />

These large (20 to 40 μm) cells may occur singly or in<br />

clumps. Clumps may be loose aggregates or may be<br />

tissue with indistinct cell borders. Nuclei are eccentrically<br />

placed <strong>and</strong> are round to oval with a definitive smooth<br />

nuclear membrane <strong>and</strong> regular nuclear contour.<br />

Chromatin is distributed evenly <strong>and</strong> is reticulated or<br />

dense; occasionally the nucleus may appear pyknotic.<br />

Nucleoli are inconspicuous. The cytoplasm is typically<br />

amphophilic <strong>and</strong> grainy but occasionally is blue (a<br />

feature <strong>of</strong> ependymal cells). Microvilli may be present<br />

(a feature <strong>of</strong> choroidal cells). Extensive degeneration <strong>of</strong><br />

choroidal <strong>and</strong> ependymal cells may occur so that only<br />

naked nuclei remain.<br />

Miscellaneous Cells<br />

Blast Cell<br />

A blast is a large, round to oval cell, 10 to 20 μm in<br />

diameter, with a high nuclear-to-cytoplasmic ratio. The<br />

blast <strong>of</strong>ten has a round to oval nucleus, but it is<br />

sometimes indented or folded. In addition,<br />

cytocentrifugation artifact may result in an irregular<br />

nuclear contour. The nuclear chromatin is typically fine,<br />

lacey, or granular <strong>and</strong> one or more nucleoli may be<br />

present Nucleoli are more prominent in cytocentrifuge<br />

slides. The cytoplasm is basophilic <strong>and</strong> <strong>of</strong>ten agranular;<br />

however, when cytoplasmic granules occur, they are<br />

more easily visualized in the cytocentrifuge slide than in<br />

peripheral blood or bone marrow smears. In the<br />

absence <strong>of</strong> lineage-associated findings, such as Auer<br />

rods, cytoplasmic granules, cytochemical data, or cell<br />

surface marker data, it is not possible to further<br />

characterize a given blast cell. This is particularly<br />

true for body fluids, where cytospin preparation<br />

artifact may alter or obscure morphologic details.<br />

Degenerative changes also may occur if the fluid<br />

specimen is not processed promptly.<br />

Chondrocyte (Cartilage Cell)<br />

Rarely, chondrocytes are obtained during lumbar<br />

puncture, probably when the needle nicks the<br />

vertebral cartilage. This is a more common occurrence<br />

in infants <strong>of</strong> adults with a narrow intervertebral space.<br />

Chondrocytes are typically seen in the synovial fluid <strong>of</strong><br />

patients with osteoarthritis, but also may occur after joint<br />

trauma or surgery.<br />

The cells have round or oval, dark nuclei which are<br />

typically centrally placed. The cytoplasm is dense <strong>and</strong><br />

wine-red. A cytoplasmic clear zone adjacent to the<br />

nucleus is <strong>of</strong>ten present <strong>and</strong> it may completely surround<br />

the nucleus.<br />

Degenerating Cells (Not Otherwise<br />

Specified)<br />

Degenerating cells with pyknotic (highly condensed)<br />

nuclei or nuclear karyorrhexis (fragmentation) may<br />

occasionally be seen in body fluids. Autodigestion or<br />

autolysis <strong>of</strong> neutrophils may occur as they attempt to<br />

remove foreign material.<br />

The nucleus becomes pyknotic <strong>and</strong> fragments <strong>and</strong> with<br />

further autolysis, may appear as one or more indistinct,<br />

light purple inclusion(s). The nuclear lobes may fragment<br />

into numerous small particles <strong>of</strong> varying sizes that<br />

resemble microorganisms. Cytoplasmic granules may<br />

become less prominent or may fuse (particularly with<br />

toxic granulation). The cytoplasmic borders may<br />

become ftayed <strong>and</strong> indistinct. Cytoplasmic vacuole<br />

formation is common.<br />

Autolytic neutrophils with eccentric, dense, round nuclei<br />

<strong>and</strong> pale cytoplasm may resemble nucleated red cells,<br />

but differ from them in the persistence <strong>of</strong> cytoplasmic<br />

granules.<br />

Actively dividing cells such as malignant cells, reactive<br />

lymphocytes <strong>and</strong> mesothelial cells, may more<br />

readily undergo degenerative changes in body fluids.<br />

The cytoplasm may show a swollen, vacuolated, or<br />

frayed appearance. The nuclear chromatin may<br />

show coarse condensations separated by enlarged<br />

parachromatin spaces (salami-like appearance).<br />

Ventricular lining cells <strong>of</strong>ten will not appear intact when<br />

shed into CSF or ventricular fluid; only bare nuclei with<br />

pieces <strong>of</strong> frayed cytoplasm will be seen.<br />

52 <strong>College</strong> <strong>of</strong> <strong>American</strong> Pathologists<br />

2012 <strong>Hematology</strong>, <strong>Clinical</strong> <strong>Microscopy</strong>, <strong>and</strong> Body Fluids <strong>Glossary</strong>

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